Field Approval for Belly Access to STEC-30 Servos

[crhannay]

I did received a Field Approval for a Belly Access Panel. This modification will improve safety by allowing access to the STEC-30 autopilot servos that are virtually inaccessible without an access panel.

See the link to paperwork in the next post.

[crhannay]

Here is a link to the basic paperwork. There is 5 more CAD drawings that you will have to pay HPAS, LLC to authorize you to use.

Johan Pieterse: n645mm@yahoo.com


https://backcountrypilot.org/me/my-phot ... bumid=6227

[zamfire]

Interesting to see an actual 337 that got approval. However that should have passed as a minor alteration. Why? Because I don't see how it:

"appreciably affects weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or

(2) That is not done according to accepted practices or cannot be done by elementary operations." 14 CFR Part 1.1

It has none of those effects, appreciable or otherwise. Therefore it's a minor alteration.

If it was my airplane, I'd argue my case with them anytime.

[Andy Young]

I’m with Zamfire on this one.

Plenty of FAA people these days will tell you that you need a field approval for anything that diverges in any way whatsoever from the way the plane came out of the factory. Then they will tell you that they don’t do field approvals anymore, and that you’ll need a one-time STC, requiring lots of expensive DER time (one your dime) with no guarantee of approval.

Most of these FAA folks have a fairly vague understanding of the FARs as they relate to maintenance. The trick is finding an A&P/IA who DOES know the regs, and isn’t afraid to use them. Unfortunately, most are too worried about liability or their relationship with the FAA to exercise their authority to determine what is and is not a major repair or alteration; they just follow the guidance of their local FAA airworthiness inspector, right or wrong.

Example: I built a simple, light armrest that attaches to the door of my Maule. An FAA inspector tried to tell me that this was a major modification, since it attaches to the door structure, and the door is part of the airframe. I told him that I found it hard to believe that the armrest appreciably affected the structural strength or performance of the airframe, given that my POH says I can fly without the door!

[crhannay]

I would agree with you in most cases but in this case I believe a Field Approval was the appropriate course of action. When you start welding parts on the fuselage tubing that is not on any approved Maule drawing you need an authorization.

[zamfire]

I wonder does the FAA actually employ engineers to look at modifications ? I have come to the conclusion that that they don't, it's paperpushers that make engineering decisions. This is just wrong. The case with the armrest is typical. The door is not a structural part of the airframe and only a bureaucrat would make such an uninformed statement. I'm not a "qualified" engineer, but I know enough to do basic stress analysis on an airplane as simple as a Maule (I dabble in homebuilt airplane design) . I will happily argue my potential modifications with any FAA employee, engineer or otherwise. And if he proves to me that what I'm doing is wrong, bad or otherwise undesirable, I'll happily accept that. But I don't take the opinion of of a penpusher with no knowledge of engineering, mechanics of even flying in general as gospel.

[crhannay]

Yes the FAA has DERs on staff.

[crhannay]

Of course every FSDO and FSFO is different. I recently ask for a Field Approval for some additional 12V outlets under the pilot seats for my headsets. They decided that it was a minor alteration even though I had gotten on for the same thing before.

[zamfire]

Funny you should mention 12 outlets; it comes up in this webinar by Mike Busch. I highly recommend this youtube channel "Savvy aviation".

In this he talks about Major and Minor alterations.

https://www.youtube.com/watch?v=Qs2d6sJfT7I&t=204s

[crhannay]

Thanks I will watch the video.
Curt